Typical full size racks are 42U, which is approximately 6 feet in height. A full size rack holds approximately twenty-one 2U chassis in uniform alignment. Each 2U chassis can include between 24 and 26 hard disk drives (HDD) of 2.5 inch size. FIG. 1A illustrates a 2U chassis configured in an HDD vertical mode. In HDD vertical mode 100, 2U chassis 102 is configured to receive between 24 and 26 HDDs 104a, 104b, 104c, . . . , 104n (collectively “104”). Each HDD 104 is enclosed in an HDD carrier configured to couple to a backplane of chassis 102. The size of the HDD carrier can be a limiting factor in the number of drives a 2U chassis can receive. FIG. 1B illustrates a 2U chassis configured in an HDD horizontal mode. In HDD horizontal mode 150, 2U chassis 102 is configured to receive 25 HDDs 104.
Thus, a typical full size rack can be configured with twenty-one 2U racks and between 504 and 546 HDDs. An HDD chassis layout and a size of the carrier of the HDD are two limitations hindering the drive capacity in a 2U chassis, and a typical full size rack.